Soil-Steaming and Steam-Boiler Blog

The reduction of roof loads due to snow is a top topic again this winter. For this reason, after the first major snow falls in higher areas new tests were made to find out which steaming methods are most efficient.

The big advantage of hot steam in contrast to classic methods to remove snow with shovels is clear: Due to the heat snow flows away as water. There is no need to first remove snow from the roof and then transport it further away from the building.

Moreover labor cost is much lower when using steam.

In order to melt 1kg of snow only 0,1691 kg of steam is needed. Efficient steam generators with an efficiency of 96% only consume 0,015l of fuel to produce this amount of steam.

In order to calculate energy cost density of snow has to be considered, which is about 0,17kg/dm³ = 170kg/m³ for fresh fallen snow.(See http://en.wikipedia.org/wiki/Snow). In order to steam 1 m³ of snow about 2,55l fuel is needed. This amount was confirmed several times in tests.

Based on this knowledge this year 4 steaming methods were tested and compared.

1. Steaming Hood

The area is covered with a light hood made of aluminium. Then hot steam is induced. The hood is moved to another location by hand once all snow has melted. The results are always 100%.

Only 15 kg of steam were used to melt all snow on an area of 3.2m² within only 4.5 minutes. (about 0,5m³/89 kg snow).

2. Steaming pipes with steaming sheets

Perforated pipes are laid out on the snow covered area in regular distances and covered with sheets. Hot steam is induced into the pipes to melt snow.

Most snow melted away. However despite the continuous induction of steam, snow isles remained as no optimal melting affect was achieved due to slightly higher snow density.

3. Steaming pipes in roof gutter

Perforated pipes are laid out in the roof gutter of a green house and continuously covered with snow from both sides while steam evaporates.

As long as the pipe is constantly covered with snow, an optimal melting affect could be achieved. However, a constant use of labor was needed to supply snow.

4. Steaming with steaming lance

Similar to a high pressure cleaner, steam gets applied via a lance and distributed manually.

Although melting was achieved, however the method was very inefficient as the majority of steam doesn’t reach the snow.

Conclusion: Melting snow with a steaming hood is the most effective method to free big areas from snow. The biggest mobile steam generators produce 2000kg of steam per hour and have about 10 times the output than the machine used in the upper mentioned tests. With such a big generator in 4.5 minutes about ~890 kg = ~5m³ of snow can be melted. Per hour a reduction of roof load by more than 65m³ = ~11t is feasible.

The new trade fair for horticulture and vegetable farming in Middle and Eastern Europe took place from the 27. 09 to the 28.09. in Vienna.
Furthermore the world’s biggest agricultural show, taking place from the 14.11. to the 19.11, was fully booked out with more than 2.500 exhibitors from 48 countries.

On both fairs the latest steaming technology was presented. Several thousand visitors could learn more about the latest innovations for soil sterilization with hot steam. For the first time the newly developed steaming system “A-1350-24” was introduced. The robot was designed and manufactured by MSD Corp., Durbach in cooperation with Fobro-Kress, CH- Hüswil. The steam robot, specialized on the efficient steaming of groomed beat cultures, such as baby leaf salads, was upgraded to double its capacity.

In addition, the current research results of the DLR Rheinlandpfalz on steaming of arugula were presented.

On the 2nd September 2011 at the forth award ceremony of the German Innovation Price Horticulture, the best innovations were awarded.
MSD GmbH belonged to the group of winners of this year. The award was presented with the following text:

The „Dämpfmobil“ developed by Firma MSD Corp. in Durbach serves the purpose of physical plant protection.

It is a new development of a mobile, fully automated steaming device for the superficial, deep penetrating treatment of large, groomed open land areas After manual set up on the field, the steaming robot operates fully automatic.

In comparison to previous systems for area steaming, the steaming robot facilitates the use of steaming and reduces operation cost per hectare, as work time and energy can be saved. This device takes thermo physical plant protection one big step further and makes it more practical.

Due to the linkage of modern technology for automation as well as the high efficiency of the used heating system it was possible to create a modern machine based on the proved process of soil steaming. For the future it is expected of such processes to grow in importance. For ecological horticulture steaming is often the only alternative.

Steaming becomes even less inexpensive. Besides the fact that steaming time can be reduced by 20% without losing the positive weed control effect of steam, recently a study revealed that yet another energy saving potential can be used.

Steam trials with arugula have shown that the 100% effect of hot steam against weeds at a steaming depth of about 8 – 10 cm persists even for the 2nd crop.
After the first and the 2nd crop no weeds were found in the arugula beets. Hence the harvest meets highest quality standards.

Conclusion:
The beets only need to be steamed once for two harvests. Please pay attention to the following: When steaming, the soil needs to be steamed a little longer down to 10cm depth. As long as the soil of the beets isn’t moved, the 2nd crop grows without any weeds. One steaming process can be saved and cost comes down by another approx. 25%!

More results of steaming were presented in Cologne / Auweiler at a field day of the agricultural chamber of the German federal state NRW.
Furthermore the DLR RLP presents its latest research results on steaming during the field day on the 15th of September 2011 in Queckbrunnerhof, Schifferstad.

The new steaming system, developed by Mobildampf in cooperation with Fobro Kress, has reached maturity. Since this month it’s ready for production.

The Steam Mixer allows variable steaming in greenhouses or on open land. It has a fixed scraper with a two-rowed hydraulic vibrating harrow at 60-200 rounds per minute (no power take off). The steam injector is corrosion-resistant and stands out due to its robust construction.
In accordance to information provided by the manufacturer, the new steaming system runs at a speed of 40-140 m / h, depending on the steaming depth of 5-15cm and on the output of the steam boiler.

The standard scope of supply contains frame, cover, rod-type rolls, steam injector, vibrating harrow, 2 steaming sheets (15m), sheet intake, hydraulic drive incl. plug-in couplings DIN 2 and throttling valve.

This machine was presented for the first time in Nuremburg on the 04th of August 2011

Similar to tree nurseries, intensively used areas in grapevine nurseries may have damaged soil and plants. Cultures with long growing cycle have a considerable risk of loss on depleted and sick soil.

After yielding extraordinarily positive results for soil steaming in vegetable gardening last year, the Service Center for Rural Areas (DLR) Rheinlandpfalz (Rhineland-Palatinate) expects similar good effects for hotsteam in vine plants growing.

On the 14th of April 2011 a special steaming method came to use. The challenge was to reach temperatures of over 90°C in up to 40 cm depth within a short period of time. A special steaming hood was used which was equipped with twelve 40 cm long steaming spikes per sqm. This method allows the induction of 60 to 80 kg steam per hour per m³ soil which reduces steaming time down to 15 minutes.

On the treated area as well as on the control area plant growth will be monitored in a long term study. Results are expected within the next 2-3 years.

In Altdorf, close to Bonn Germany, the Service Center for Rural Areas (DLR) Rheinlandpfalz (Rhineland-Palatinate) conducts another steaming trial. The regeneration of soil for tree and shrug cultures is in the focus. After the successful application of hot steam in growing vegetables in the last two years that reaped astonishing effects such as an increase of growth to up to 30% and the complete killing of weeds, the leading research institute is also convinced that steam can solve the most important issues in fruit and berry growing.

The problems which appear in such cultures are manifold. In particular harvests can be distroyed by soil fatigue and other soilborne pathogens such as nemathodes, fungi and bacteria which may cause the grower to close down.

Hence it is important that the soil is healthy and clean before planting. The use of pesticides becomes more and more problematic. Now steam shall be the alternative.

The DLR Rheinlandpfalz treated an area of altogether 200m² at the beginning of April 2011. The area was covered with heat resistant sheets. Through a special steam injector steam was induced underneath the sheets for 4 hours. During this time steam penetrated the soil down to 30-35 cm depth and heated it up to at least 85°C. Right after steaming new plants were planted on the area.

In the upcoming months positive effects are expected in particular such as plant growth and increase of harvest.